Creep strength variations related to grain boundaries in the equiatomic CoCrFeMnNi high-entropy alloy

Compression and tensile creep of the equiatomic CoCrFeMnNi high-entropy alloy was investigated at 1073 K and 1253 K. The high-entropy alloy was either in the polycrystalline or monocrystalline solid solution state. We find that the polycrystalline variant creeps significantly faster than the monocry...

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Bibliographic Details
Published in:Scripta materialia 2024-08, Vol.249 (C), p.116165, Article 116165
Main Authors: Záležák, Tomáš, Gadelmeier, Christian, Gamanov, Štěpán, Glatzel, Uwe, Inui, Haruyuki, George, Easo, Dlouhý, Antonín
Format: Article
Language:English
Subjects:
CoCrFeMnNi equiatomic alloy
Creep
Dislocations
Grain boundaries
Recovery
Single crystal
Solid solution
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Summary:Compression and tensile creep of the equiatomic CoCrFeMnNi high-entropy alloy was investigated at 1073 K and 1253 K. The high-entropy alloy was either in the polycrystalline or monocrystalline solid solution state. We find that the polycrystalline variant creeps significantly faster than the monocrystalline variant at low applied stresses. Additionally, the stress exponent is lower for the polycrystalline samples (n ∼ 3) than the monocrystalline samples (n ∼ 5), which, according to a standard interpretation of creep data, implies a curious transition from viscous glide to climb-controlled creep. Such a transition is difficult to rationalize given that our alloy composition and crystal structure remain the same and only the microstructure changes from polycrystalline to monocrystalline. We offer an alternative to the standard view where grain boundaries, which are only present in the polycrystalline material, serve as efficient sinks for dislocations and thus contribute to faster creep. [Display omitted]
ISSN:1359-6462
1872-8456
DOI:10.1016/j.scriptamat.2024.116165